In conventional railcars, various devices, such as a main electric motor, a main transformer, a circuit breaker, an arrester (lightning arrester), a main converter, and an air compressor, are provided under a floor of the railcar.
For example, in the railcar described in PTL 1, a pantograph is provided on a roof of a car, and a vacuum circuit breaker (circuit breaker), an arrester, a main transformer, a main converter, a main electric motor, and the like are provided under a floor of the car. Power collected by the pantograph is supplied to respective devices through a power cable extending from on the roof to under the floor. Especially, in the railcar that travels at a comparatively high speed, in order to lower the center of gravity and reduce noises in consideration of the increase in speed, many devices, such as a power supply unit, an auxiliary device, and an air conditioner, and cables connecting these devices are provided under the floor in addition to the above devices.
Further, in PTL 2, the electrical connection between the main transformer and the high-voltage device box provided under the floor of the car is realized by electric wires and the like. The electric wires are covered with simple coatings for preventing damages during work. Therefore, an insulating protective tube is provided for the purpose of protecting the electric wires and the like from rain water and dust and preventing accidents, such as electric shock. FIG. 9 is a diagram showing the connection structure between the high-voltage device box and the main transformer, the connection structure using the insulating protective tube. A reference sign 13 shows a circuit breaker. A reference sign 18 shows an insulator type cable head of a power cable 270 extending from on the roof. A reference sign 12 shows a high-voltage device box accommodating the circuit breaker 13. A reference sign 20 shows a main transformer. A reference sign 6 shows an insulating protective tube. A reference sign 15 shows a connection electric wire connecting the circuit breaker 13 and the insulator type cable head 18.
The power collected by the pantograph flows from the power cable 270 to the circuit breaker 13. Then, the power is supplied to the main transformer 20 through a connection electric wire 16 and a high-voltage insulator (not shown) protected by the insulating protective tube 6. Since the insulating protective tube 6 prevents electric shock by securing an insulation distance between the insulating protective tube 6 and the connection electric wire 16, it is comparatively large in size. Further, since the insulating protective tube 6 is made of metal, it is large in mass. The insulating protective tube 6 is fixed to the high-voltage device box 12 and the main transformer 20 by a plurality of bolts, screws, and the like and is sealed by applying putty for preventing intrusion of rain water and dust. When manufacturing and maintaining the car, a worker gets under the car and faces upward to perform work of attaching and detaching the insulating protective tube 6. Further, the work of attaching and detaching the circuit breaker 13 and the connection electric wire 16 is performed by using a tool or the like through an inspection lid (not shown) provided at the high-voltage device box 12.